During the Classical period (450-330 B.C.) three important temples were erected on the ruins of earlier ones: the Parthenon, the Erechtheion, and the Temple of Nike, dedicated to Athena Parthenos, Athena Polias, and Athena-Apteros Nike, respectively. The Propylaea, the monumental entrance to the sacred area was also constructed in the same period.
The monuments on the Acropolis reflect the successive phases of the city's history. Some of them were converted into Christian churches, houses of the Franks and later on, of the Turks. After the liberation of Athens from the Turks, the protection, restoration and conservation of the monuments was one of the first tasks of the newly-founded Greek state. This major effort is continued until today, with the large-scale restoration and supporting of the monuments, which started in the 1970's and is still in progress.
The first excavations on the hill were conducted between 1835 and 1837. More systematic work was carried out in 1885-1890 by Panagiotis Kavvadias.